The present invention relates to filtering or trapping particles in the flow through a valve, particularly particles found in water flowing through an electrically operated valve of the type employed in appliances connected to a municipal or household water supply. Such valves are commonly used in controlling water flow in appliances such as dishwashers, clothes washing machines and refrigerator ice makers. Such appliance water valves typically are operated by a low-current solenoid operator with only a few ounces or grams of force available for opening and closing the valving element. Such valves are thus susceptible to the effects of small foreign particles in the water supply becoming trapped on the valve seat or between moving parts which results in failure of the valve to close and leakage.
Heretofore, filter screens having a fine mesh or small openings therein for trapping minute particles in the valve inlet have been employed to prevent such particles from becoming lodged between the movable valve member and the valve seat. However, the fine mesh of such wire filter screens has shown a propensity in service to become clogged with an accumulation of trapped particles from the water supply resulting in diminished or blocked flow to the valve. In order to remedy this situation, users have disconnected the valve from the water supply and forcibly removed the filter screen to permit flow into the valve. Once the filter screen has been removed from the valve, the valve is left unprotected from foreign particles; and, experience has shown that the valve is soon caused to leak from particles lodged between the valving member of the valve seat.
Thus, it has long been desired to provide a cost effective way of providing residual filtering or blockage of particles to a supply valve after deliberate removal of the primary filter screen by the user.